Cities are machines for making the future.

A terrific E.P.A. study highlights what I’ve long said, that urban form (compactness, housing size, walkability, transit-orientation) is the elephant in the room, when it comes to climate change.

For instance, it finds that single-family rowhouses in walkable neighborhoods use 42% less total energy than detached single-family houses in auto-dependent places.

Of course clean energy is critical; of course we want more efficient technologies; of course we need to eat less (and better) meat — climate change is a complex issue, with many solutions. But climate change is a land use problem first. Our land use underlies nearly all our other climate problems.

Changing how our cities are planned, built and run is the key to humanity’s survival. Unborn generations will care far more about that than any other thing we’re doing (with the possible exception of how we handle nuclear weapons and waste).

Cities are machines for making the future. Right now, they make a sweltering future of climate chaos and suffering. They could make a bright green future. We choose.